The two clubs have finally reached agreement on the fee to bring an end to a summer-long pursuit.

Chelsea released Jose Bosingwa earlier in the summer and have spent most of the window pursuing Azpilicueta as a replacement.

The former Spain Under-21 international, who represented his country in their disastrous Olympics campaign, is expected to slot straight into Roberto Di Matteo's team at right-back, where his main competition comes from veteran Paulo Ferreira and the versatile Branislav Ivanovic.

A product of Osasuna's youth system, he made his La Liga debut aged 17 and was a first-team regular at 18 before moving to the Stade Velodrom in 2010.

A knee injury kept him on the sidelines for six months in his first season at Marseille in but he went on to fully establish himself in the team last season.